1. Field
The following description relates to a relay and a terminal in a multi-pair two-way network and a communication method thereof.
2. Description of Related Art
Systems have been developed that enable interaction and networking between users of devices configured to transmit and receive information over a variety of network types. To this point, 1% of all devices existing globally are able to connect to other devices over a network. However, technology development and device integration have enabled an expectation of further development to implement vast networks utilized by smart phones, sensor devices, and the like requiring connectivity to other networked devices of varied functionality. Further, many users expect to use these types of communication devices to readily share content, perform synchronization and output, and utilize various applications and games through direct contact with other networked devices of varied functionality.
One of the conventional approaches to enabling this direct contact via a network is through a multi-pair two-way relay network. Here, a two-way relay channel is a channel through which two terminals or users exchange data using a relay. The multi-pair two-way relay channel is two-way relay channels formed by a plurality of nodes.
A conventional scheme used to perform data transmission via the multi-pair two-way relay channel is a decoding and forward and amplified and forward scheme. As an example, an environment is assumed in which three pairs of two-way relay channels are superposed.
When a half duplex is assumed to be a transmission scheme, twelve time slots are required to exchange all data. In this example, a network capacity, i.e., a transmission capacity of a network, is inversely proportional to a number of time slots. Therefore, the transmission capacity of the network is reduced to be inversely proportional to the number of users. A decrease in the transmission capacity may occur since different resources, for example, different time slots, are used for each transmission, as opposed to using an appropriate interference management scheme.
When a network coding is assumed in a two-way relay of a unit-pair, a time slot decreases to half of the time slot. However, the unit-pair uses resources with other pairs by dividing the resources. As a result, six time slots may be expanded in the two-way relay of the unit-pair. The six time slots are used since the transmission capacity of the network decreases to be inversely proportional to the number of the terminals or users. Therefore, when the number of terminals or users increases rapidly, the transmission efficiency in the network decreases.
As a result, a wireless access technology is desired that supports direct communication among devices, or device-to-device (D2D) communication that performs data transmission using a multi-hop structure, in addition to a cellular communication based on a conventional infrastructure. In addition, a method is desired that supports this type of direct communication to effectively communicate using a two-way relay formed by multiple nodes.